Half a million copies of Windows 8—and probably more than that by now—are officially in the wild, says Microsoft CEO Steve Ballmer. Microsoft released a preview version of its upcoming tablet-angled Windows-rethink on Tuesday, and it looks like 500,000 copies leapt across the digi-sphere in less than 24 hours.

“While it’s clear we have a long way to go still with Windows 8, we’ve been gratified by the reactions and the interest,” said Ballmer at Microsoft’s BUILD conference (via Bloomberg).

That said, it looks like Microsoft’s battling misinformation about what the tablet version of its new operating system will and won’t run. According to Information Week, Microsoft’s Stephen Sinofsky says that apps written for Intel x86-based Windows PCs won’t run on ARM-processor-based Windows 8 tablets (Sinfosky’s the president of Microsoft’s Windows division).

“We’ve been very clear since the very first CES demos and forward that the ARM product won’t run any x86 applications,” said Sinofsky yesterday, reframing comments he made on Tuesday, in which he implied the Windows 8 demos shown were “equally at home” on both x86 and ARM systems.

But while compiling different versions of the same apps probably wouldn’t be impossible, the issue (per Sinofsky) is that tablets and PCs are different animals, thus apps will need to be designed to take advantage of the pros (and mitigate the cons) of each platform.

Makes sense to us, though it feels like a step backwards toward the good ol’ Windows 95 vs. Windows NT days.

[UPDATE: It looks like Information Week got its wires crossed—a Microsoft spokesperson wrote to say as much, and to clarify: “When a developer writes a Metro style application, all the tools are there to enable them in any of the languages that we support to automatically support ARM or x86. Essentially, if a developer creates an app using the Metro style application, it will work on both x86 and ARM.”]